A woman suffered broken ribs after being swallowed by a sinkhole that opened under her feet while she was walking along a sidewalk in northwest China on Sunday.

A surveillance camera captured footage of the incident at around 6pm, showing the woman dressed in black walking along a sidewalk in Lanzhou in Gansu Province, Sohu.com reported.

A large hole, measuring about three meters square, suddenly appeared beneath the woman, causing her to disappear into a dark void in the sidewalk as it collapsed.

A female passer-by who witnessed the incident said pedestrians found there was nothing to support the sidewalk at that point, just a big holed with staircases on the side underneath.

The woman alerted other pedestrians not to come over as she feared more people would fall into the sinkhole.

The woman was later rescued by construction workers and passers-by and sent to the hospital for medical treatment.

They said she suffered broken ribs but her life did not appear to be in danger. The area was cordoned off and the case is being investigated by local authorities.